I know this has been discussed but thought I'd bring it up again as I've seen some questions about some specific points and I've had an argument or two as well. Here is the FAA regulation. 

 

Sec. 91.117 — Aircraft speed.

a] Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).

 

b] Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph "b" does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.

 

c] No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph).

 

d] If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.

 

So I have a few questions:

 

1) what is minimum safe airspeed? 

 

2) if a heavy has a clean speed of 270kts can he fly the departure by regulation at 270kts, i.e. without permission, and if so does he need to inform the controller or does he inform the controller as a matter of courtesy?

 

3) if he has to ask the controller for permission how can the controller give him permission to do something against regs? Or is the controller considered an Administrator?

 

4) how long does an aircraft need to fly over 250kts before it is considered an infraction? I'm assuming that on descent when there is no reason to exceed 250kts that a few seconds at 253kts is not going to get anyone upset. Will 30 seconds at 260kts cause an uproar, or would it take a minute at 300kts? I guess technically anything over 250kts is against the rules but what is the situation in real life? 

 

 

 

 

Good question Bill, especially since this is the center of a ton of confusion in the sim community.

 

 

 

1) what is minimum safe airspeed? 

 

This is a tough one, as there is no direct reference in the FAA regulations that specifically states a particular aircraft configuration for where min safe would apply. This is where a lot of simmers (and even some pilots who don't have heavy experience) like to assert that the pilot would leave the flaps slats out to meet the restriction.

 

The main point that the aircraft's config is never specified is a valid argument since it's never declared in a regulatory sense, but 91.117a and d exemptions would be listed in the company's approved OPSpec, which is enforceable as if it were an FAR (for that particular operator). So, it's not defined in the broad sense, but it's defined by the operator and approved by the Administrator (or designee thereof at an FAA FSDO).

 

To counter the latter point, I point to the fact that climb profiles are defined by the manufacturer, and the performance data is based off of those profiles. Alteration of the climb profile would render the data unreliable, which could be seen as a safety of flight issue. Again, though, this is all rendered irrelevant by whatever ends up being put in the OPSpec.

 

 

 

2) if a heavy has a clean speed of 270kts can he fly the departure by regulation at 270kts, i.e. without permission, and if so does he need to inform the controller or does he inform the controller as a matter of courtesy?

 

The pilot should fly at the required speed (as defined in their OPSpec) and NOT report.

 

The ATC Handbook (JO 7110.65) notes in 5-7-2 a Note 1 that "A pilot operating at or above 10,000 feet MSL on an assigned speed adjustment greater than 250 knots is expected to comply with 14 CFR Section 91.117(a) when cleared below 10,000 feet MSL, within domestic airspace, without notifying ATC. Pilots are expected to comply with the other provisions of 14 CFR Section 91.117 without notification."

(emphasis mine)

 

ATC is not expecting it, and the pilots should not report it (at fields like MEM for FDX's early morning push, this would unnecessarily clutter the frequency).

 

Many people try to counter with "well I heard ABC pilot report it this one time on LiveATC," but just because it's been heard doesn't mean that it's correct. How many times have people heard pilots asking for clearance into Class C airspace? I've heard it a ton of times, but the controller responding to the callsign is implicit clearance, per AIM 3-2-4 c 3 Note 1.

 

 

 

3) if he has to ask the controller for permission how can the controller give him permission to do something against regs? Or is the controller considered an Administrator?

 

FAR 183 makes no provisions for controllers to act as the Administrator, so this is not something a controller may approve. Controllers may not waive FARs - 91.117a makes this clear.

 

 

 

4) how long does an aircraft need to fly over 250kts before it is considered an infraction? I'm assuming that on descent when there is no reason to exceed 250kts that a few seconds at 253kts is not going to get anyone upset. Will 30 seconds at 260kts cause an uproar, or would it take a minute at 300kts? I guess technically anything over 250kts is against the rules but what is the situation in real life? 

 

The following only applies to arrivals, as by the time you're an arrival, your weight should be well below the requirements for a higher min safe speed (as defined by the company OPSpec). Departures are a lot heavier given their higher fuel loads. There are a few exceptions, for certain aircraft, but I can't think of any that would be that heavy on arrival.

 

The only people truly watching all of this unfold in real time are the controllers. The controllers, however see groundspeed (at least that's the only thing immediately available on the scope - ADS-B adds a bunch of data to the data steam, but it's not displayed by default), and not indicated airspeed. The indicated airspeed is what the reg is defined by.

 

Controllers are not the police of the sky, so if it's a momentary excursion above 250, and it doesn't cause you to get too close to another aircraft, it's very likely it won't be noticed or reported. A couple knots would likely be seen as just the effects of wind (again, remembering controllers only see GS and not IAS). More than a few knots might be noticeable, and the controller might prompt the pilot with "say indicated," but even that is usually just a poke at the pilot to pay attention and get it in check. If there is a massive difference, however, and the pilot is clearly above 250 where it causes a conflict, there are strong chances that it will get reported. Loss of separation occurred and it was because of a pilot deviation, so they'll want to make that known because the loss of sep wasn't entirely their fault.

 

The main piece here is that you have to fit into the flow. The only time it's going to be obvious is if you're going a lot faster than the aircraft around you.

1) Minimum safe speed is usually minimum maneuver speed clean. This is the optimum speed by the manufacturer that give you best turn rate and bank protection.

 

2) From my personal experience, no permission is required and the controller can't grant this request. All aircraft performance and procedures are certified during certification. As far as the departure goes, it depends. Let's say there is a turning departure with a max speed which protects you from terrain. In this case, you would delay configuration in order to keep a tight radius. Most departures don't have a max speed unless they are trying to keep you from spilling outside of the departure turn. Once you are through the turn, you can accel to clean up. In the DC10s i flew the climb speed profile states. V2/V2+10 To Accel height, 250/min maneuver speed which ever highest, 10,000ft acccel to 330, 29,000 intercept 0.825 up to cruise. I've never asked any where in the world when going above 250 and was never questioned.

 

Keep in mind that profiles are designed to give the best performance in engine out and climb performance. There's no way you are expected to keep flaps hanging while engine out or trying to meet a climb restriction. There are no obstacle and climb charts for that performance. Only takeoff configuration engine out. After clean up, these charts are in the clean configuration.

 

3) Not in FAA airspace.

 

4) This all depends, I've been with a guy in a G3 and had the controller request our indicated while he was just hitting 5 knots over. These guys usually don't know your indicated. He sees you are moving faster than the other traffic, so he will query you. In new technology, like in the 550s I fly, he sees my indicated with my squawk. He also sees my altitude window settings. I've never heard of a guy getting busted for speed, you just hear the random indicated inquiry which tips you off. Sometimes they ask because you are following or being followed. Happens alot in DC airspace. He/she will ask someone their indicated and then instruct me to maintain that speed or lower. 

 

 

The main point that the aircraft's config is never specified is a valid argument since it's never declared in a regulatory sense, but 91.117a and d exemptions would be listed in the company's approved OPSpec, which is enforceable as if it were an FAR (for that particular operator). So, it's not defined in the broad sense, but it's defined by the operator and approved by the Administrator (or designee thereof at an FAA FSDO).

 

In Canada operators have an Operations Manual that is approved by Transport Canada. I assume the OPSpec is the equivalent for operators in the US?  I can't find anything with Google--are these manuals confidential or is there a way to find out what certain airlines (Delta, for example) have as policy concerning the 250kt rule?

In Canada operators have an Operations Manual that is approved by Transport Canada. I assume the OPSpec is the equivalent for operators in the US?  I can't find anything with Google--are these manuals confidential or is there a way to find out what certain airlines (Delta, for example) have as policy concerning the 250kt rule?

 

It seems like your reference to Transport Canada is similar. Here's the FAA language:

http://fsims.faa.gov/WDocs/8900.1/V03%20Tech%20Admin/Chapter%2018/03_018_003.htm

 

You probably won't find much about specific OPSpecs online, as they contain things that the operators probably view as competitive advantages, related to how they specifically operate. Additionally, they're not shared because they're only applicable to the crews who fly for them. I have no need for a DAL OPSpec because I'm not bound by the agreements within it. I do understand the curiosity, though.

 

DAL's policy is likely just like most everyone else's, though: clean up and fly the speed the FMC commands, per the 91.117d exemption.

Kyle, yes, it looks like the Canadian Operation Manual and the US OPSpec manual are the same thing. 

 

The problem is that if Minimum Safe Airspeed is not clearly defined in the FAA regs, but rather in OPSpecs of the individual airlines, we don't really know for sure and are back to where "a lot of simmers (and even some pilots who don't have heavy experience) like to assert that the pilot would leave the flaps slats out to meet the restriction." Unless the real world pilots can share what their OPSpecs manuals say or said we're no closer to nailing it. 

Kyle, yes, it looks like the Canadian Operation Manual and the US OPSpec manual are the same thing. 

 

The problem is that if Minimum Safe Airspeed is not clearly defined in the FAA regs, but rather in OPSpecs of the individual airlines, we don't really know for sure and are back to where "a lot of simmers (and even some pilots who don't have heavy experience) like to assert that the pilot would leave the flaps slats out to meet the restriction." Unless the real world pilots can share what their OPSpecs manuals say or said we're no closer to nailing it. 

 

Right, but you have two people in here who have real world aviation experience telling you exactly what you need to know. Rick flew DC10s, and I consulted with that FAA for a while (mostly on the ATC side, but also with the group at HQ). So, it's not an ongoing issue of "nobody's actually nailed it." It's been nailed. Twice in this very thread.

 

I can nearly guarantee you're never going to come across an OPSpec that specifies that you must remain under 250 by some means (like leaving the flaps out). If you want a practical inference, listen to the LiveATC archives of the FDX MEM departure push. You'll be listening to heavy DC10s, MD11s and 777s all leaving with tons of cargo and fuel, most likely all needing to be above 250 knots. Not once will you hear a pilot request a higher speed, but you'll still see speeds that can be worked out to above 250 on FlightAware (there are many IAS to TAS converters online, though the wind speed data will be tougher to track down).

 

I see where you're coming from regarding the information being hard to come by, but most of the issue here is a bunch of people not knowing what they're talking about, but passing their ideas off as fact. This is especially evident with the VAs and all of their reporting programs. Their "landing competitions" go against the guidance that a landing should be firm, too, particularly if the weather is less than ideal (windy or wet).

https://www.dropbox.com/s/b148p2ddt7nj66t/takeoff2.jpg?dl=0

 

https://www.dropbox.com/s/h7vd6gq6fcwuhaw/minman.jpg?dl=0

 

Just to give him an idea, these two are from my DC10 flight manual. One tells the speed to fly after clean up and the other shows the clean up speeds and schedule.

Thanks Rick. I'm assuming Vmm is minimum clean speed? 

Obviously 91.117d is a US requirement. Out of interest the UK legal reqirement is:
 

Speed limitations

21 (1) Subject to paragraph (2), an aircraft shall not fly below flight level 100 at a speed
which, according to its air speed indicator, is more than 250 knots.

(2) Paragraph (1) shall not apply to:

(a) flights in Class A airspace;

( B) VFR flights or IFR flights in Class B airspace;

© IFR flights in Class C airspace;

(d) VFR flights in Class C airspace or VFR flights or IFR flights in Class D airspace
when authorised by the appropriate air traffic control unit;

(e) an aircraft taking part in an exhibition of flying for which a permission is required
by article 80(1) of the Order, if the flight is made in accordance with the terms of
the permission granted to the organiser of the exhibition of flying and in
accordance with the conditions of the display authorisation granted to the pilot
under article 80(6)(a) of the Order;

(f) the flight of an aircraft flying in accordance with the A Conditions or the B
Conditions; or

(g) an aircraft flying in accordance with a written permission granted by the CAA
authorising the aircraft to exceed the speed limit in paragraph (1).

(3) The CAA may grant a permission for the purpose of paragraph (2)(g) subject to such
conditions

However the limitation 250kts/10,000ft on SIDs is still an air traffic control instruction which has to be complied with.

According to the UK regulations you can't fly above 250kts without ATC approval and it's not even clear in the above regs that ATC is allowed to grant it. Or am I reading it wrong?

 

 

According to the UK regulations you can't fly above 250kts without ATC approval and it's not even clear in the above regs that ATC is allowed to grant it. Or am I reading it wrong?

 

Outside controlled airspace, that is (I think) true. However, in practice the only people likely to be operating above 250kts below FL100 in Class G are Her Majesty's Flying Club and the rule doesn't apply to them either ;-).

 

In class A, B (not currently in use in the UK) and C the restriction doesn't apply full stop to IFR aircraft, but there is normally a charted restriction (which could be lifted by ATC). VFR in class C and both IFR and VFR in class D must adhere to 250 below FL100 but again ATC can authorise high speed (when authorised by the appropriate air traffic control unit).

 

The difference between the UK (and most of the rest of the world) and the US is that US ATC are not legally allowed to lift the restriction under any circumstances, whereas over here, as outlined above, ATC are in most cases explicitly authorised to lift the restriction.

 

 

Thanks Rick. I'm assuming Vmm is minimum clean speed?

 

Vmm is the minimum clean maneuvering speed that ensures up to 44 degrees of bank stall protection.

Another point is that that the "minimum safe airspeed for any particular operation" regulation doesn't apply in the UK. Does any know where else in the world applies, other than US and Canada?

I used to hear Emirates in their 777 telling the controllers "min clean is 270 today" and some would authorize them to accelerate prior to 10,000.  I think its traffic permitting.

 

Sometimes I have a min clean of 245-255.  I just leave the slats out until 10,000 or if the route is pretty much straight ahead.